<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            border: 0;
        }

        body {
            width: 100vw;
            height: 100vh;
            overflow: hidden;
        }

        .box {
            display: flex;
            flex-flow: column;
            justify-content: space-between;
            height: 100%;
        }

        /* 头部 */
        .heard {
            flex-basis: 45px;
            background-color: pink;
            display: flex;
        }

        /* 内容 */
        .content {
            flex-grow: 1;
            /* background-color: green; */
            display: flex;
            /* position: relative; */
            /* height: 100vh; */
        }

        .content_box {
            display: flex;
            width: 100%;
            /* position: absolute; */
            /* height: 575px; */
            /* top: 45px; */
            /* bottom: -45px; */
            /* z-index: -1; */
        }

        .left {
            flex-basis: 60px;
            background: linear-gradient(180deg, #ddd, #ccc, #ddd)
        }

        .right {
            flex-grow: 1;
            background-color: red;

        }

        /* 底部 */
        .footer {
            flex-basis: 45px;
            display: flex;
            overflow: hidden;
        }

        .footer div {
            flex-grow: 1;
            display: flex;
            /* border-right: 1px solid #ddd; */
            flex-direction: column-reverse;
            position: relative;
        }

        h4 {
            flex: 0 0 50px;
            display: flex;
            text-align: center;
            flex-direction: column;
            justify-content: center;
            cursor: pointer;
            color: white;
            background-color: pink;
        }

        .box_ul {
            /* position: absolute; */
        }

        .box_ul ul {
            list-style: none;
            display: flex;
            flex-direction: column-reverse;
            text-align: center;
            margin: 5px;
            border: 1px solid #ddd;
            /* background-color: red; */
            border-radius: 5%;

        }

        .box_ul ul li {
            flex: 1 0 50px;
            display: flex;
            justify-content: center;
            flex-direction: column;
            border-bottom: 1px solid #555;
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="heard">头部</div>
        <div class="content">
            <div class="content_box">
                <div class="left">左边</div>
                <div class="right">右边</div>
            </div>
        </div>
        <div class="footer">
            <div>
                <h4>首页</h4>
                <div class="box_ul">
                    <ul>
                        <li>css</li>
                        <li>js</li>
                        <li>vue</li>
                    </ul>
                </div>
            </div>
            <div>
                <h4>功能</h4>
            </div>
            <div>
                <h4>更多</h4>
            </div>
        </div>
    </div>
</body>

</html>